(1) Field of the Invention
The field of the invention is data transmission.
(2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Media extenders or media converters are commonplace in today's digital age, with such devices being incorporated in such industries as machine vision, broadcasting, or personal computer industries. Such devices are used to carry media streams, either video or voice, with constant data rates, from the stream data source, e.g., cameras, video cards, disc players, to the stream data sink, e.g., image capture cards, display panels, image processors, etc. The purpose of using such devices includes long distance transmission, networked switching, intermediate data processing, etc, where the original media stream data needs to be transformed into an appropriate format to serve the purpose and then converted back to its original format before it arrives at the data sink.
Because the original media stream data is transformed and transmitted over an asynchronous link with respect to its original data rate, the stream clocking information is lost. When reconstructing the stream data at the receiver end, a scheme is required to generate an emulated stream clock whose average frequency is the same as the original stream clock so that the stream data can flow through the system continuously and lossless.
Further complications are that for different type of stream data source or different vendor/configuration of the same type of stream data source, the data rates can vary across a big range. For example, the Camera Link™, a widely used interface in the machine vision industry, is defined to have a data clock frequency from 20 MHz to 85 MHz. The DVI interface clock can vary from 25 MHz to 165 MHz. The system should be able to carry over the stream data without knowing the nominal frequency in advance, except the possible frequency range.
There have been previous attempts to generate an emulated stream clock in a data transmission application. Some examples can be found in U.S. Pat. Nos. 6,721,323, 6,072,810 and 7,212,598 (herein incorporated by reference in their entireties).
All referenced patents, applications and literatures are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. The invention may seek to satisfy one or more of the above-mentioned desires. Although the present invention may obviate one or more of the above-mentioned desires, it should be understood that some aspects of the invention might not necessarily obviate them.